Preheat your oven to the temperature recommended on the puff pastry package (usually around 400°F/200°C). Line baking sheets with parchment paper.
On a lightly floured surface, unfold the thawed puff pastry sheets. Use a rolling pin to gently roll out each sheet to your desired thickness. Cut each sheet into rectangles or desired shapes for individual pizzas.
Place the cut puff pastry pieces onto the prepared baking sheets, leaving some space between each one. Brush the edges of each pastry piece with the beaten egg and water mixture to create a golden crust when baked.
Spread a thin layer of marinara pizza sauce over each puff pastry piece, leaving a small border around the edges. Layer the mozzarella cheese on top of the sauce. If using additional toppings (bell peppers, mushrooms, onions, olives, spinach, red pepper flakes), distribute them evenly over the cheese.
If desired, sprinkle freshly grated Parmigiano-Reggiano cheese on top for added flavor. Place the baking sheets in the preheated oven and bake for about 15-20 minutes or until the puff pastry is golden brown and the cheese is bubbly and melted.
Once done, remove the puff pastry pizzas from the oven and let them cool for a few minutes. Before serving, garnish with torn fresh basil leaves for a burst of flavor and freshness.
Serve the puff pastry pizzas warm and enjoy!